class_docstr: Class to retrieve IOCs from ThreatStream.com and store them in DynamoDB
code: def __init__(self, function_arn, timing_func):
      self._config = self._load_config(function_arn)
      self.timing_func = timing_func
      self.api_user = None
      self.api_key = None
  
imports: from datetime import datetime, timedelta
  import json
  import backoff
  import boto3
  from botocore.exceptions import ClientError
  import requests
  from streamalert.shared.backoff_handlers import backoff_handler, success_handler, giveup_handler
  from streamalert.shared.config import load_config, parse_lambda_arn
  from streamalert.shared.logger import get_logger
  from streamalert.threat_intel_downloader.exceptions import ThreatStreamCredsError, ThreatStreamLambdaInvokeError, ThreatStreamRequestsError
label_desc: Use image node_id 1 to create a new ThreatStream object  with example: obj = ThreatStream(function_arn, timing_func)